Binders used in road works and associated applications comprise bitumen or acrylic-type, vinylic latexes, derived from crude oil and petrochemistry. These binders are thus obtained from fossil originating resources.
Bitumen is used in various applications because of its cementing value. Indeed, it adheres to most traditional materials such as stone, concrete, wood, metals and glass. Furthermore, it is an outstanding thermal and dielectric insulating material.
Nowadays, a lot of pavements, if not all, are coated with bituminous mixes which have demonstrated their ability on the one hand to positively answer to application constraints and, on the other hand, to endure traffic high strains and changeable climatic conditions. Such mixes or coatings are composed of aggregates bound together with bitumen or with bitumen that has been modified by adding additives, especially elastomers and/or thermoplastic polymers. Bitumen-bound aggregates are also used for building and public works in order to make amongst others waterproofing layers, sidewalk coatings, ripraps, coatings for engineering structures. In addition, bitumen is used in so-called industrial applications like waterproofing or sound and heat insulation.
Bitumen is a material derived from crude oil processing. As such, it belongs to raw materials that are said to be non renewable as crude oil is a fossil material.
The gradual exhaustion of the crude oil resources leads to the need for developing novel binders that could replace, in various applications, the traditionally used bituminous binders.
The American U.S. Pat. No. 5,021,476 describes a binder for making an elastic road pavement comprising a mineral or vegetable process oil, a resin of vegetable origin selected from a tall oil resin, a wood resin, a turpentine resin or a combination of these resins, an elastomer and a thermoplastic polymer. The previously mentioned elastomers and thermoplastic polymers are derived from a petrochemical raw material. Such binders are thus substantially not derived from renewable raw materials.
There are also binders of substantially vegetable origin used in road applications. The European patent EP 1466878 discloses binders having a natural origin prepared from a vegetable resin such as rosin or derivatives thereof and from a vegetable oil. However, these binders suffer from gaining their performance only after a curing time of at least several hours, that is to say after the drying agents have reacted with oxygen in air.
Therefore, there is a need for making non bituminous binders especially based on a renewable raw material, that could replace in various applications binders composed of non renewable components such as traditionally used bituminous binders and/or petrochemical, synthetic or semi-natural resins.
To help preserve the environment, those binders should preferably be biofragmentable, biodegradable and have a low ecotoxicity. These products should moreover be preferably made of natural raw materials with no synthetic homolog at a reasonable price.
Lastly, there is also a need for preparing natural raw material-containing resins with thermoplastic properties especially for road applications. Indeed, thermoplastic resins acquire their mechanical properties upon cooling and thus do not suffer from having a long curing time.